The long-term goals are to comprehensively characterize extraocular muscles (EOMs) at the molecular level. Precise functioning of EOMs is an absolute requirement for optimal vision in humans. EOMs are highly specialized and undergo a wide range of reflexes/motions and the detailed properties of EOMs are different from those of other muscles. Enigmatically, EOMs have differential sensitivity to certain diseases. EOMs have prominent involvement in myasthenia gravis, Grave's disease and mitochondrial myopathies;they are spared, however, in Duchenne muscular dystrophy (DMD), despite the widespread involvement of all other skeletal muscle groups. Our central thesis is that EOMs are fundamentally different from other skeletal muscles;and that we can trace their unique properties and disease susceptibilities to unique patterns of their molecular constituents;a 'molecular barcode'. During the past funding period we have comprehensively defined the EOM 'transcriptome'and 'proteome'. These studies provide us with many insights into EOM function and provide us with a global picture of the unique molecular signature of EOM. While supporting our central thesis, the molecular characterization is as yet incomplete. A number of hypotheses remain unaddressed regarding differential expression in EOMs of newly discovered classes of regulatory molecules (e.g. microRNAs), expression differences at the subcellular level (e.g. sub-synaptic or NMJ regional expression) or indeed functional consequences of differential gene expression (e.g. altered calcium handling) in EOMs vs limb muscles. To test these hypotheses we propose: a) to define the EOM 'miRNAome', validate miRNA expression differences and create an EOM mRNA-miRNA interactome database;b) to define the transcriptome at the sub-synaptic (NMJ) regions of EOM and identify alterations to the sub-synaptic transcriptome due to visual deprivation, and, c) characterize expression of calcium regulatory molecules and calcium homeostatic mechanisms in EOM. The health relatedness of this project is that by completion of these aims we will ensure clearer understanding of the molecular and functional diversity of EOMs, their biomechanical properties, insights into pathophysiology of these unique muscles and therapeutic development for disease. PUBLIC HEALTH RELEVANCE: The health relatedness of this project is that by completion of our aims we will ensure clearer understanding of the molecular and functional diversity of EOMs as well as their biomechanical properties as well as insights into of these unique muscles.